openapi-typescript

What is openapi-typescript?

The openapi-typescript npm package is a tool that generates TypeScript types from OpenAPI specifications. This helps developers ensure type safety and better integration between their API definitions and TypeScript code.

What are openapi-typescript's main functionalities?

Generate TypeScript Types

This feature allows you to generate TypeScript types from an OpenAPI specification URL. The generated types are then saved to a file named 'types.ts'.

const openapiTS = require('openapi-typescript');
const fs = require('fs');

async function generateTypes() {
  const types = await openapiTS('https://api.example.com/openapi.json');
  fs.writeFileSync('types.ts', types);
}

generateTypes();

Generate Types from Local File

This feature allows you to generate TypeScript types from a local OpenAPI specification file. The generated types are saved to a file named 'types.ts'.

const openapiTS = require('openapi-typescript');
const fs = require('fs');
const path = require('path');

async function generateTypes() {
  const types = await openapiTS(path.join(__dirname, 'openapi.json'));
  fs.writeFileSync('types.ts', types);
}

generateTypes();

Custom Type Generation Options

This feature allows you to customize the type generation process by providing options such as a transform function. The transform function can be used to modify the schema before generating the types.

const openapiTS = require('openapi-typescript');
const fs = require('fs');

async function generateTypes() {
  const types = await openapiTS('https://api.example.com/openapi.json', {
    transform: (schema) => {
      // Custom transformation logic
      return schema;
    }
  });
  fs.writeFileSync('types.ts', types);
}

generateTypes();

Other packages similar to openapi-typescript

swagger-typescript-api

The swagger-typescript-api package generates TypeScript API client code from Swagger/OpenAPI definitions. It provides more advanced features like generating API client methods and supports both Swagger 2.0 and OpenAPI 3.0 specifications.

typescript-fetch

The typescript-fetch package is a generator for TypeScript clients using the Fetch API. It generates TypeScript code from OpenAPI specifications and is particularly useful for creating client-side code that interacts with RESTful APIs.

README

📘️ openapi-typescript

🚀 Convert OpenAPI 3.0 and 2.0 (Swagger) schemas to TypeScript interfaces using Node.js.

💅 The output is prettified with Prettier (and can be customized!).

👉 Works for both local and remote resources (filesystem and HTTP).

View examples:

• Stripe, OpenAPI 2.0
• Stripe, OpenAPI 3.0

Usage

CLI

🗄️ Reading specs from file system

npx openapi-typescript schema.yaml --output schema.ts

# 🤞 Loading spec from tests/v2/specs/stripe.yaml…
# 🚀 schema.yaml -> schema.ts [250ms]

☁️ Reading specs from remote resource

npx openapi-typescript https://petstore.swagger.io/v2/swagger.json --output petstore.ts

# 🤞 Loading spec from https://petstore.swagger.io/v2/swagger.json…
# 🚀 https://petstore.swagger.io/v2/swagger.json -> petstore.ts [650ms]

Thanks to @psmyrdek for the remote spec feature!

Using in TypeScript

Import any top-level item from the generated spec to use it. It works best if you also alias types to save on typing:

import { components } from './generated-schema.ts';

type APIResponse = components["schemas"]["APIResponse"];

The reason for all the ["…"] everywhere is because OpenAPI lets you use more characters than are valid TypeScript identifiers. The goal of this project is to generate all of your schema, not merely the parts that are “TypeScript-safe.”

Also note that there’s a special operations interface that you can import OperationObjects by their operationId:

import { operations } from './generated-schema.ts';

type getUsersById = operations["getUsersById"];

This is the only place where our generation differs from your schema as-written, but it’s done so as a convenience and shouldn’t cause any issues (you can still use deep references as-needed).

Thanks to @gr2m for the operations feature!

Outputting to stdout

npx openapi-typescript schema.yaml

Generating multiple schemas

In your package.json, for each schema you’d like to transform add one generate:specs:[name] npm-script. Then combine them all into one generate:specs script, like so:

"scripts": {
  "generate:specs": "npm run generate:specs:one && npm run generate:specs:two && npm run generate:specs:three",
  "generate:specs:one": "npx openapi-typescript one.yaml -o one.ts",
  "generate:specs:two": "npx openapi-typescript two.yaml -o two.ts",
  "generate:specs:three": "npx openapi-typescript three.yaml -o three.ts"
}

If you use npm-run-all, you can shorten this:

"scripts": {
  "generate:specs": "run-p generate:specs:*",

You can even specify unique options per-spec, if needed. To generate them all together, run:

npm run generate:specs

Rinse and repeat for more specs.

For anything more complicated, or for generating specs dynamically, you can also use the Node API.

CLI Options

Option	Alias	Default	Description
--output [location]	-o	(stdout)	Where should the output file be saved?
--prettier-config [location]			(optional) Path to your custom Prettier configuration for output
--raw-schema		false	Generate TS types from partial schema (e.g. having components.schema at the top level)

Node

npm i --save-dev openapi-typescript

const { readFileSync } = require("fs");
const swaggerToTS = require("openapi-typescript").default;

const input = JSON.parse(readFileSync("spec.json", "utf8")); // Input can be any JS object (OpenAPI format)
const output = swaggerToTS(input); // Outputs TypeScript defs as a string (to be parsed, or written to a file)

The Node API is a bit more flexible: it will only take a JS object as input (OpenAPI format), and return a string of TS definitions. This lets you pull from any source (a Swagger server, local files, etc.), and similarly lets you parse, post-process, and save the output anywhere.

If your specs are in YAML, you’ll have to convert them to JS objects using a library such as js-yaml. If you’re batching large folders of specs, glob may also come in handy.

Migrating from v1 to v2

Migrating from v1 to v2

Project Goals

1. Support converting any OpenAPI 3.0 or 2.0 (Swagger) schema to TypeScript types, no matter how complicated
2. The generated TypeScript types must match your schema as closely as possible (i.e. don’t convert names to PascalCase or follow any TypeScript-isms; faithfully reproduce your schema as closely as possible, capitalization and all)
3. This library is a TypeScript generator, not a schema validator.

Contributing

PRs are welcome! Please see our CONTRIBUTING.md guide. Opening an issue beforehand to discuss is encouraged but not required.

Contributors ✨

Thanks goes to these wonderful people (emoji key):

Drew Powers 💻 📖 🚇 ⚠️	Przemek Smyrdek 💻 📖 🤔 ⚠️	Dan Enman 🐛 💻	Atle Frenvik Sveen 💻 📖 🤔 ⚠️	Tim de Wolf 💻 🤔	Tom Barton 💻 📖 🤔 ⚠️	Sven Nicolai Viig 🐛 💻 ⚠️
Sorin Davidoi 🐛 💻 ⚠️	Nathan Schneirov 💻 📖 🤔 ⚠️	Lucien Bénié 💻 📖 🤔 ⚠️	Boris K 📖	Anton 🐛 💻 🤔 ⚠️	Tim Shelburne 💻 ⚠️	Michał Miszczyszyn 💻
Sam K Hall 💻 ⚠️	Matt Jeanes 💻	Kristofer Giltvedt Selbekk 💻	Elliana May 💻 ⚠️	Henrik Hall 💻 📖	Gregor Martynus 💻 ⚠️ 🐛	Sam Mesterton-Gibbons 💻 🐛 ⚠️
Rendall 💻 🐛 ⚠️	Robert Massaioli 💻 🐛	Jan Kuča 💻 ⚠️	Thomas Valadez 📖	Asitha de Silva 💻 🐛	Mikhail Yermolayev 🐛	Alex Batalov 💻 ⚠️
Federico Bevione 🐛 💻 ⚠️

This project follows the all-contributors specification. Contributions of any kind welcome!